A lighter bullet may shoot lower. There's two equations at work here, it's a max/min situation. Generally speaking, a bullet fired at sedate velocities will shoot higher with a heavier bullet. Stepping up the velocity with the same bullet may lower it some, sometimes. At the other end, a lighter bullet will shoot lower, generally. It has to do with bullet barrel time and the recoil of the rifle/pistol. I found I couldn't shoot a 300 grain bullet from my Black Hawk. It printed 15" high at 50 yard with the rear sight lowered all of the way. You might be able to go with a 200 grain bullet and solve the sight problem, but you still have an issue if you want to hunt with the rifle. I prefer heavy bullets over light ones. I'd rather go with a 240 than a 200 grain bullet. It may be you need to change to an aperture sight. The advantages of an aperture are they not only give you a longer sight radius, they also put the target and sights in one plane which minimizes old eye problems if you want to shoot the Puma, but they also allow for more vertical adjustment over the barrel mounted front sight. Personally, I prefer a Marble tang sight which has both click windage and elevation adjustments and is solid as opposed to a Lyman #2 which has no windage adjustment and tends have lateral flop. Additionally, the tang will also give a longer sight radius than will a receiver mounted sight. Even though you've been advised to get a taller front sight which you might still need, I'd still get an aperture for the reasons listed above. In other words, get the aperture first and if it doesn't work, try a taller sight. Either way, you still have the inherent accuracy provided by the aperture.
